The general flip-top electronic devices such as notebook computers, mobile phones or the like usually have a display device and a host body pivotally coupled together through a pivotal apparatus. In general the pivotal apparatus mainly includes an axle and two connection members hinged on the axle to couple respectively with the display device and the host body. When in use the display device can be flipped against the host body in an unfolding state to perform operation as desired. When not in use, the display device can be folded over the host body in half. Through the pivotal apparatus the size of the flip-top electronic device can be greatly shrunk to facilitate storing and carrying.
Conventional pivotal apparatus, such as those disclosed in Taiwan patent Nos. 1463078, M483333, M471736 and M466462, mainly include a holding seat, two axles located abreast on the holding seat to couple respectively with a display device and a host body, and two torsional force generation members corresponding to one of the axles. Because the two axles are arranged abreast the pivotal apparatus cannot be shrunk to a smaller size. As a result, the electronic device employed the pivotal apparatus cannot be thinned as desired. In addition, the torsional force generation member used on the conventional pivotal apparatus is formed by stacking a plurality of elastic blades, and the tightness between the elastic blades is adjusted by wrenching an adjustment nut mounted onto the torsional force generation member, thereby provides a swivel torsional force to the axle. However, because the conventional structure deploys the torsional force generation member on one of the axles, during assembly each torsional force generation member requires torsional force adjustment. Such a practice cannot guarantee the two axles receiving same amount of torsional force during turning. Hence there is still room for improvement.